TestClient timeout simulates http.disconnect

[Kludex]

• Supersedes TestClient timeout simulates http.disconnect #751
• Closes add basic timeout support for testclient #1109
• Closes Disconnect event not received when using TestClient #1247

There's an alternative timeout meaning on #1109, but I think we should proceed with this idea, as I can already see three usages:

• Test StreamingResponse properly
• Test Add listener for disconnect to FileResponse #1427
• Test Allow background tasks to run with custom BaseHTTPMiddleware's #1441

Missing:

• docs
• Replace requests timeout exception by starlette native one

[lovelydinosaur]

My honest opinion on this is that we pretty much shouldn't be changing TestClient at all, until #1376 is in.

(I'm also not convinced by supporting timeout on the TestClient. It's okay for these things to have some constraints. It's not something that eg. Django's TestClient has, it's not something that the httpx.WSGITransport or httpx.ASGITransport cases support, and I'd be absolutely okay with Starlette not supporting it directly either.)

[Kludex]

Would you have a recommendation on how to test the tests mentioned on the description? i.e. when we have an http.disconnect on the application.

[lovelydinosaur]

For now, I'd just suggest "The TestClient doesn't support timeouts. If you need to test this kind of behaviour you'll need to do so using ASGI messaging directly".

[Kludex]

Thanks